I'm sorry to hear about your recent loss.
We recently lost two of our family cats. Both had been with me for 18+ years so I insisted on being present at the end. Bonnie was at the e-vet. And it wasn't pleasant. She did receive a sedative before the final shot but it was all very rushed and I wasn't comfortable.
Clyde went with our vet and was a completely different experience. The sedative was administered, Clyde went to sleep and I was left alone with Clyde to spend a few moments with him. The vet and nurse returned and the final shot was administered.
I'm sorry your experience was terrible. That's not something you need to deal with at this time.